PowerBuilder (pb)的扩展DLL开发（超级篇）（二）
FROM:https://blog.csdn.net/lxbin2003/article/details/118214878?spm=1001.2014.3001.5502原创：lxbin2003
PB的扩展DLL开发（超级篇）（二）
(PB史上第一次开放的开发技术)
上一章（PowerBuilder (pb)的扩展DLL开发（超级篇）（一）
https://www.sybasebbs.com/forum.php?mod=viewthread&tid=90013&fromuid=6）里，我们说到system library 里的函数声明为下面这样的方式。
__declspec(dllexport) DWORD __stdcall FuncName(POB_THIS obThis,int nArgCount)
{
BOOL isnull;
return 1;
}
其中第一个参数POB_THIS obThis 是每个函数的核心，本篇重点介绍一下核心结构OB_THIS，它是每个函数的第一个参数。这个结构有点大，通常我们不需要直接访问成员结构，但了解了这个结构的成员，有时候可以很方便地访问一些全局的内容。
typedef struct ob_this {
void* __vtbl;
POB_THIS obthis; // 兼容性指针
POB_THIS rtthis; //兼容性指针
PSH_DBG_THIS dbgthis; //调试时使用
ppbstg_anchor stgthis; // 指向内存分配的锚，有些函数需要用到它，比如pbstg_alloc
UINT curr_pcode; // Current pcode Instruction
BOOL pcode_done; // End of pcode block indicator.
PSHLIST pBreakPointList; // 指向断点列表
INT bStep; // Processing step mode
RT_BREAK_PROC rtBreakCallback; // Debugger call back function
PVOID pUserData; // 给用户使用，存放用户数据。
PSHLIST pTransactionList; // 事务列表
BOOL bIgnoreErrors; // Ignore runtime error flag
BOOL bTerminateRuntime; // Terminate runtime flag
OB_CLASS_HNDL clshndl; // Current class handle
OB_CLASS_HNDL appclshndl; // Application class handle
OB_EVT_ID event_id; // Event ID
OB_INST_ID appinst; // Application实例对象
pbstg_subpool subpool; //指向内存分配的池，有些函数需要用到它，比如pbstg_alloc
RT_MODE mode; // 模式，比如编译状态、EXE运行状态、调试状态等
PVOID smthis; // Semantic this pointer
OB_MODE obMode; // Object manager mode
UINT iPCodeCounter; // PCode execution counter
RT_OPT_MODE opt_mode; // Optimization mode
PSHLIST pDllList; //已经加入的外部DLL列表，即程序里那些声明DLL函数用到的DLL
PVOID curr_pcode_blk; // Current pcode block
UINT iContextCount; // Number of run contexts
// only valid in primary rtthis
BOOL bHaltClose; // Halt close processing flag
BOOL bDontTerminate; // Dont terminate after error
UINT curr_line_block_loc; // Current line_block loc.
UINT last_break_line_no; // Last line numbers...
UINT last_pcode_line_no; // ...
PVOID FAR* pThreadStart; // Points to start of thread
PVOID FAR* pThreadNode; // Points to cur. thread node
UINT halt_close_nest; // Count of nested halt close
PCM_THIS cmthis; // Current compiler context
PSHLIST pLibraryList; //库列表，SetLibraryList 函数就是设置此列表
PSHLIST pNameList; // Library entry name list
PVOID pGroupList; // Pointer to group list nodes
PVOID pLookSymKeyFunction; // Group name hash key function
PVOID scnthis; // Scanner this pointer
UINT iGroupListIncr; // Group list increment
UINT iGroupListPos; // Group list position
UINT iGroupListSize; // Group list size
pbstg_subpool client_subpool; // Client subpool
pbstg_subpool perm_subpool; // Permanent subpool
pbstg_subpool result_subpool; // Intermediate results
pbstg_subpool temp_subpool; // Temporary subpool
PSHLIST group_stack; // List of groups ids currently in use
PVOID curr_obj_group;
PVOID sys_typedef_group;
PVOID curr_routnode;
OB_INST_ID curr_obinst;//当前对象实例，比如 json.Set(…)调用时，Set函数里的当前对象就指向json这个实例。
PVOID lib_handle;
PSHLIST run_stack; // Used to maintain Runtime Call Stack
PVOID rtinst_stack; // Used to maintain instance list
LPTSTR def_appl_groupname; //创建 target 时指定的 application名称
LPTSTR def_appl_libname; //创建 target 时指定的pbl ,通常名称与 application一样，但后缀名是 .pbl
PVOID appl_group;
BOOL bInRuntime;
UINT appl_filter;
PVOID hExecutable;
UINT iExeGroupCounter;
PSHLIST pExeGroupList; // No longer used
PVOID pExeResourceHash; // Resource list for build .EXE
POT_EVAL_NODE expr_stack; // maintain params and vars used by pcodes
UINT expr_stack_size; // size of expression (data) stack
POT_EVAL_NODE expr_stack_ptr; // current stack entry
PSHLIST arglist_stack; // NOT USED
PSHLIST error_list; // list of errors during application build
BOOL bGotLinkError;
pbstg_subpool lvalue_subpool; // Lvalues
BOOL bNoDuplicateSymbols;
PSHLIST unused; // UNUSED
OB_CLASS_HNDL curr_class_hndl;
OB_ARRAY_ID curr_array_inst; // Current array inst id.
UINT ErrorCode;
BOOL set_return_called;
OB_GROUP_HNDL sys_group_hndl;
PVOID pSavedGroupList; // Pointer to saved group list nodes
PVOID lmithis; // Ptr to Lib Mgr anchor
PVOID curr_runstk_node; // Ptr to runtime stack node.
ULONG ps_options; // PS executable options
OB_EXE_CODE_TYPE exe_code_type; // CCode or PCode
LPTSTR pExecutableName; // current executable
PVOID evaled_arglist; // 每个函数调用时，这里是实际参数数组指针，可用ot_get_....arg(…) 系列函数来取具体参数，也可以 for(int i=0;i来循环直接取参数
// from expr_stack and converted as necessary
PVOID lvalue_info;
UINT curr_arg_pos; //保留取当前参数的位置。函数开始时，此变量为0，用ot_get_....arg(…)每取走一个参数时，此变量会增加。如果取参数的次数大于实际参数个数，会导致程序崩溃。因此取参数时最好要判断此变量不大于参数个数 nArgCount。
POT_EVAL_NODE return_value; //
POT_EVAL_NODE called_return_value; //函数调用结束，实际返回值存放在这里。通常用 ot_set_return_val(…) 来设置，或者 ot_no_ret_val(obThis) 来表明无返回值。
PVOID p_error_info; // Error information for CCode
LONG routine_level; // the routine level for CCode
ULONG ulDServFlags; // Flags for distributed PB
PVOID working_group; // Current working group
PVOID callback_data; // Used to store pointer for
// callback functions.
PVOID callback_data2; // 2nd instance
POB_THIS parentObThis; // The obthis that was cloned to
BOOL check_for_locked_menu;// used by 'obinst.cpp' - Currently only used in local object create.
// can be easily removed
//***************************************************************************
// file I/O buffers
//***************************************************************************
LPTSTR pEntryBuffer;
TCHAR HUGEPTR* pHugeEntryBuffer;
LONG lEntryPos;
LONG lEntrySize;
//***************************************************************************
// Multi-Tasking, Transaction Pooling, Miscellaneous
//***************************************************************************
PVOID pTransPool; // Transaction Pool
// this growblock is used as an array of groupId's to enable the codegen
// routines to be thread safe and still be able to load the context.
PSH_GROWBLOCK pGroupIdArray;
PVOID criticalSection; // general purpose critical section
PVOID pCmCompilerError; // so we can decouple compiler dll
ULONG GeneralFlags;
PVOID unused_2; // some free bytes for the taking ...
BOOL bIgnoreLinkErrors; // ignore link errors.
UINT new_next_pcode; // User set pcode Instruction
PVOID pSharedObjMgr; // shared object manager inte**ce
// trace facility
LPVOID traceStruct; // tracing structure
BOOL bTracing; // global trace enable flag
// debugger facility
PSHLIST pWatchPointList; // Pointer to watchpoint list
PSHLIST dbg_callstk; // Stack for walking up call stack
UINT bStepLine; // Line number for step to cursor
INT bStepRoutineLevel; // Depth step command started at
// secure runtime session
ULONG SecureRuntimeSession; // flags for apps downloaded over the Web.
// garbage collection
DWORD lGCTimeLimit; // the min time between garbage collection runs
DWORD lLastGCTime; // the time of the end of the last GC run
BOOL bGarbageCollecting; // if we are in the process of garbage collecting
// object manager request queue
PVOID pRequestQueue; // a pointer to the obj_mgr request queue
// pointer to error callback function for handling runtime errors
PVOID pErrorCallback;
// windows dispatch handler
PVOID pWndDispatchHndlr; // a pointer to the dispatch handler
// these should all be protected by ob_enter_critical_section()!!
DWORD idOwnerThread; // the handle the of thread that owns the OBTHIS
BOOL bActiveSession; // indicate that this obthis is an active session
BOOL bIsAsyncCall; // indicates if root of call is async
PVOID pLocalSession;
PVOID local_variables; // Current local variables to routine
UINT num_variables; // Number of local variables.
UINT curr_stack_bias; // Current stack bias. Used for gc.
BOOL bDeferredDelete; // indicates if we are deferring the delete
// of an active session until after all requests
// have completed processing.
// Context Feature OB_ICONTEXT pointers
PVOID pSessOB_ICONTEXT;
PVOID pDefltOB_ICONTEXT;
// Class Definition (a.k.a. metaclass) local session list
PSHLIST pSessionList;
LPTSTR lpstrTypdefPblName; // if we want to ignore the default of "pbtypvm70.dll"
BOOL bNoMessageBoxForError; // TRUE if we don't want the message box to come up.
BOOL bInSystemError; // TRUE if we are already executing the system error event.
PVOID last_break_routine; // Last routine a breakpoint was processed in.
BOOL bInitDebugMode; // Are we in the debugger and NOT running from within it.
PVOID pContextObject; // The context object
// remote debugger facility
PVOID pLocalDebugSession; // If non-NULL, the local debug session for Remote debugging
ULONG breakpointId; // unique id for breakpoints
// GroupLoader stuff.
PVOID pGroupLoader;
//Resulset Marshaling
PVOID pResultsetInfo;
// pointer to error callback state information for functions handling runtime errors
PVOID pErrorCallbackState;
// Exception Handling
PSHLIST exception_stack; // stack containing the checked exception list
PVOID thrown_exception; // pointer to thrown exception object,
// NULL if none pending
PVOID curr_exception; // pointer to currently handled exception object,
//NULL if not currently handling one
PSHLIST gosub_stack; // stack containing the list of gosub return locations
struct ResponseWindowStack
{
ResponseWindowStackNode* stack;
UINT capacity;
UINT count;
} response_window_stack;
PSHLIST objects_creating; // A list object being created.
PVOID pb_session; // To be used for PSPP
PVOID pMetaObject; // A pointer to the meta object created by a func call
// and need to be free in the next sf_dot call.
// PB Accessibility service
/*这部分 pb9 没有
PVOID pACCService;
BOOL isInOrcaBootStrap;
LPTSTR pCurrMissedTypeWhenOrcaBootStrap;
BOOL bInNewBuild;
PVOID pb_sessionA;
BOOL bJITStart;
BOOL bJITOption;
*/
} OB_THIS;
OB_THIS这个结构比较复杂，有必要对它进行一些研究和了解。
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原文链接：https://blog.csdn.net/lxbin2003/article/details/118214878
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